updating docstrings
removing positions property and misc rearrangements
replace Point class with Vector class and update methods accordingly
removing positions property and implement check_type function
rearranging future imports
replacing except KeyError as e with just except KeyError
rely on duck-typing for building atoms list
removing check_type method
Removing remaining calls to `check_type` method.
adding new constructor parameter to control property list updating
updating code for LAMMPSAtom and LAMMPSAtoms to subclass Atom and Atoms
remove isinstance check for Atoms and rely on duck-typing
testing LAMMPSAtom class